The invention relates to a multilayer, composite, fleece material having a core layer and at least one cover layer attached to the core layer, where the at least one cover layer is needled with the core layer such that fibers of the at least one cover layer protrude into the core layer.
Such composite materials may be used in the manufacture of the interior panels of vehicles, for example, automobile headlinings, where the basic structure of the composite material might look like the following: A ply or cover layer made from organosynthetic fibers, natural fibers, or glass fibers is arranged on that side of the composite material facing the vehicle's roof. An adhesive foil or powdered adhesive that binds the cover layer to a reinforcing layer is applied to this cover layer. The reinforcing layer might, for example, consist of foam, organosynthetic fibers, natural fibers, or glass fibers. An adhesive foil or powdered adhesive, with which a second cover layer is bonded to the reinforcing layer, is applied to the opposite side of the reinforcing layer, i.e., this side thereof facing the vehicles interior. The second cover layer may also consist of organosynthetic fibers, natural fibers, or glass fibers, and is usually covered with a decorative layer.
Other composite materials used for manufacturing automobile headlinings have already been described in conjunction with the state of the art. For example, a composite material for manufacturing the headlinings of vehicle roofs that consists of three, superimposed layers is known from German Patent DE 697 17 662 T2. All three layers consist of short, hot-melting, polyester fibers having a low melting point, where the intermediate layer is much thicker than the outer layers and contains polyester fibers having a lower melting point. The intermediate layer and outer layers are bonded together using a preheating process, under which the polyester fibers melt. A decorative layer may be applied to the laminated layers.
Another composite, fibrous-fleece component is known from German Patent DE 103 19 967 A1. The composite, fibrous-fleece component consists of a mixed-fiber fleece that contains higher-melting-point, thermoplastic fibers and reinforcing fibers. The mixed-fiber fleece may, preferably, be strengthened by needling. A composite foil that is composed of a layer of a higher-melting-point, thermoplastic plastic and a layer of a lower-melting-point, thermoplastic plastic is provided on one, or both, sides of the mixed-fiber fleece, where the layer of lower-melting-point, thermoplastic plastic faces the mixed-fiber fleece. The mixed-fiber fleece and composite foil are heated by a heat source to a temperature above the melting points of the thermoplastic fibers of the mixed-fiber fleece and the lower-melting-point, thermoplastic plastic of the composite foil such that they adhere to one another in order to bond them together.
German Patent DE 102 97 710 T5 also describes a fiber-reinforced, composite material and a method for manufacturing such a composite material. The composite material comprises a composite mat that has thermoplastic fibers and reinforcing fibers that are needled together. The composite mat is heated in order to melt the thermoplastic fibers and compressed, yielding a composite foil. The composite foil is reheated following compression, which yields a pseudofoamed, composite foil due to the inherent elasticity of the reinforcing fibers.
Manufacturing molded components, such as headlinings or other components of vehicle interiors, from a needled fleece is also known from German Patent DE 100 07 556 A1, where the needling of the fleece is such that 50% of the needlings penetrate at least 60% of the thickness of the fleece, without penetrating all the way through it.
However, these composite materials which are known from the state of the art have a number of disadvantages. Mixtures of materials that are bonded together using adhesives and might also contain glass fibers for reinforcement are usually difficult to recycle, or cannot be recycled. Emission of pollutants into vehicle interiors may also occur, depending upon the raw materials employed. Furthermore, it might be observed that sagging due to thermal expansion occurs. Poor acoustic properties may be observed if duroplastic materials are employed. Those problems may be alleviated by employing needled, fleece materials, although they usually exhibit very low rigidities.